Miniature loudspeaker module, method for enhancing frequency response thereof, and electronic device

Abstract

The present invention discloses a miniature loudspeaker module, a method for enhancing frequency response of a miniature loudspeaker module, and an electronic device. The method comprises the steps of: additionally providing a passive driver in a cavity where an active driver of a miniature loudspeaker module is located, the passive driver and the active driver radiating together, wherein, after the passive driver is additionally provided in the miniature loudspeaker module, the amplitude of a vibrating diaphragm of the active driver shows a local dip on frequency bands below a resonant frequency point F 0 , and the lowest point of the local dip is corresponding to a frequency point Fb; and, perform, according to amplitude characteristics of the vibrating diaphragm of the active driver of the miniature loudspeaker module additionally provided with the passive driver, matching enhancement to an input signal of the active driver. In the technical solutions provided by the present invention, as the frequency response of the whole miniature loudspeaker module on low frequency bands below F 0 is enhanced after a passive driver is additionally provided, and matching enhancement is further performed to signals according to the amplitude characteristics of the active driver, the frequency resource of the miniature loudspeaker module on the whole frequency band is enhanced greatly.

The invention claimed is: 
     
       1. A method for enhancing frequency response of a miniature loudspeaker module, wherein the method comprises the steps of:
 additionally providing a passive driver in a cavity where an active driver of the miniature loudspeaker module is located, the passive driver has a vibrating diaphragm, and the passive driver and the active driver radiating together; 
 wherein, after the passive driver is additionally provided in the miniature loudspeaker module, an amplitude characteristics of a vibrating diaphragm of the active driver shows a local dip frequency on frequency bands below a resonant frequency point F 0  which is a low frequency resonance point of the miniature loudspeaker module additionally provided with the passive driver, and the lowest point of the local dip frequency is corresponding to a frequency point Fb; and 
 performing, according to the amplitude characteristics of the vibrating diaphragm of the active driver of the miniature loudspeaker module additionally provided with the passive driver, matching enhancement to an input audio signal of the active driver; 
 wherein the performing, according to the amplitude characteristics of the vibrating diaphragm of the active driver of the miniature loudspeaker module additionally provided with the passive driver, matching enhancement to an input audio signal of the active driver comprises: 
 filtering out the input audio signal below a first frequency point which is a frequency point below the Fb, to filter out signals having an amplitude beyond an allowable range of the vibrating diaphragm of the active driver on frequency bands below the Fb; 
 performing band-pass filtering and enhancement to the input audio signal within a certain frequency band taking the Fb as a central frequency point, to realize low-frequency descending and bass enhancement; 
 performing notch filtering to the input audio signal within a certain frequency band taking the F 0  as a central frequency point, to avoid too large amplitude of the vibrating diaphragm of the active driver near the F 0 ; and 
 performing high-pass filtering and enhancement to the input audio signal above a second frequency point higher than the F 0 , and enhancing mid and high frequency response by using the characteristic of small amplitude of the vibrating diaphragm of the active driver on mid and high frequency bands. 
 
     
     
       2. The method according to  claim 1 , wherein,
 the miniature loudspeaker module is of a front porting design, and the passive driver and the active driver share a front cavity, and sound outlets are provided at positions directly facing the passive driver and the active driver in the cavity; 
 or, 
 the miniature loudspeaker module is of a front porting design, and the passive driver and the active driver share a front cavity, and a common sound outlet is provided at a position directly facing the passive driver and the active driver in the cavity; 
 or, 
 the miniature loudspeaker module is of a side porting design, and the passive driver and the active driver share a front cavity. 
 
     
     
       3. The method according to  claim 1 , wherein the method further comprises the steps of:
 adjusting the Fb by changing the coefficient of stiffness of the passive driver; and/or, adjusting the F 0  by changing the property of the vibrating diaphragm and the quality of voice coil of the active driver; and 
 adjusting, according to the values of the Fb and the F 0  and the characteristics of both a power amplifier and the amplitude of the vibrating diaphragm, one or more of the following parameters of a filter during the matching enhancement: Q value, order, frequency band attenuation parameter and cutoff frequency. 
 
     
     
       4. A miniature loudspeaker module, comprising a cavity and an active driver disposed in the cavity, wherein the miniature loudspeaker module further comprises a passive driver and a audio chip;
 the passive driver is disposed in the cavity where the active driver is located, the passive driver has a vibrating diaphragm, and the passive driver and the active driver radiate together; 
 wherein, after the passive driver is additionally provided in the miniature loudspeaker module, an amplitude characteristics of a vibrating diaphragm of the active driver shows a local dip frequency on frequency bands below a resonant frequency point F 0  which is a low frequency resonance point of the miniature loudspeaker module additionally provided with the passive driver, and the lowest point of the local dip frequency is corresponding to a frequency point Fb; and 
 the audio chip is configured to performing, according to the amplitude characteristics of the vibrating diaphragm of the active driver of the miniature loudspeaker module additionally provided with the passive driver, matching enhancement to an input audio signal of the active driver; comprises: 
 filter out the input audio signal below a first frequency point which is a frequency point below the Fb, to filter out signals having an amplitude beyond an allowable range of the vibrating diaphragm of the active driver on frequency bands below the Fb; 
 perform band-pass filtering and enhancement to the input audio signal within a certain frequency band taking the Fb as a central frequency point, to realize low-frequency descending and bass enhancement; 
 perform notch filtering to the input audio signal within a certain frequency band taking the F 0  as a central frequency point, to avoid too large amplitude of the vibrating diaphragm of the active driver near the F 0 ; and 
 perform high-pass filtering and enhancement to the input audio signal above a second frequency point higher than the F 0 , and enhancing mid and high frequency response by using the characteristic of small amplitude of the vibrating diaphragm of the active driver on mid and high frequency bands. 
 
     
     
       5. The miniature loudspeaker module according to  claim 4 , wherein,
 the miniature loudspeaker module is of a front porting design, and the passive driver and the active driver share a front cavity, and sound outlets are provided at positions directly facing the passive driver and the active driver in the cavity; 
 or, 
 the miniature loudspeaker module is of a front porting design, and the passive driver and the active driver share a front cavity, and a common sound outlet is provided at a position directly facing the passive driver and the active driver in the cavity; 
 or, 
 the miniature loudspeaker module is of a side porting design, and the passive driver and the active driver share a front cavity. 
 
     
     
       6. The miniature loudspeaker module according to  claim 4 , wherein,
 the Fb is adjusted by changing the coefficient of stiffness of the passive driver; and/or, the F 0  is adjusted by changing the property of the vibrating diaphragm and the quality of voice coil of the active driver; and 
 according to the values of the Fb and the F 0  and the characteristics of both a power amplifier of the system and the amplitude of the vibrating diaphragm, one or more of the following parameters of a filter is adjusted during the matching enhancement: Q value, order, frequency band attenuation parameter and cutoff frequency. 
 
     
     
       7. An electronic device, wherein the electronic device comprises the miniature loudspeaker module according to  claim 4 . 
     
     
       8. The electronic device according to  claim 7 , wherein the electronic device is a mobile phone, a tablet computer, a tablet television set or a notebook computer.